The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.
For high-frequency radio communications systems such as those that receive and transmit data over millimeter wave frequency bands in the range of 30 GHz to 300 GHz, the frequency response of passive low pass filters used in transmit and receive chains of wireless communications devices often have a slope in the passband signal. The drop in the passband signal at the cutoff frequency (Fc) can be pronounced.
Often, the drop in the passband signal is caused by the low-Q and the self-resonant frequency (SRF) of the on-chip spiral inductors of the passive low pass filter. For example, for 60 GHz wireless applications where the cutoff frequency (Fc) can be around 1 GHz, the drop in the frequency response of the passband signal caused by the filter can be between 3 and 5 dB at the cutoff frequency (Fc).
In addition to the passband signal slope caused by the filter, the mixer and baseband amplifiers in the chain can also have a slope in the passband signal. Overall, the frequency response of the entire chain may have too much slope in the passband signal for a baseband chip or a radio frequency integrated circuit (RFIC) chip to work with.
What is needed are techniques for reducing the slope in the passband signal in the receive chain and the transmit chain of wireless communications devices.